President Trump deserves real credit for the thaw in North Korea — not sole credit, surely, but credit nonetheless. And he achieved this, in large part, by being a jerk.

Trump's jerkiness is hardly the only factor in this Korean spring. If former South Korean President Park Geun-hye hadn't imploded in a blaze of corruption, for instance, paving the way for the dovish President Moon Jae-in, Trump would likely still be at the mean-tweeting state of his relationship with North Korea's Kim Jong Un. But Moon was so unnerved by Trump's "fire and fury" bluster and talks of military strikes last year, he pursued an almost recklessly idealistic push for peace.

Trump did not accomplish this through normal diplomatic maneuvers. He did it by being a real jerk.

America's president called another world leader "Little Rocket Man" and a "sick puppy" whose "nuclear button" is small and inadequate. The Trump team "ended Strategic Patience and ramped up sanctions," John Delury, a North Korea expert at Yonsei University in Seoul, told Axios, and "then they ramped up the military threat, and because we all thought [Trump] was crazy enough to take us to war," a window for peace opened.

If Ronald Reagan had "peace through strength," Trump has "peace through jerkiness."

It's not just his tweeting. Trump really "likes it when 'experts' are on CNN freaking out," a White House official told Axios after Trump abrogated the Iran nuclear deal on behalf of America, another jerk move, given strong public support for the accord among Americans and America's strongest allies (with the lone and notable exception of Israel's prime minister). Trump was also arguably a jerk to pull America out of the Paris climate agreement, the Trans Pacific Partnership, and any number of other multilateral deals negotiated under his predecessor, Barack Obama, who he clearly disdains.

But jerkiness works sometimes, in no small part because it creates the sort of chaos and unpredictability in which Trump revels.

"No one knows what I'm going to do," a Trump confidant paraphrased the president saying about his upcoming meeting with Kim, to Axios' Jonathan Swan. "They are over there trying right now to analyze every statement I'm putting out to get a sense of what's going to happen when I walk into the room. But the fact of the matter is nobody knows." Another source told Swan: “Kim Jong Un's entire lineage is having people think he might be crazy. Trump's like: 'You're crazy? How about this?'"

In other words, he enjoys jerking people around, viewing it as a form of strategic flexibility.

Presidential "doctrines" are usually overblown in importance. But with Trump, the doctrine matters because, like so much else about Trump, his foreign policy is all about him. "Let me tell you, the one that matters is me," Trump told Fox News in November, in response to a question about the conspicuously large number of vacancies at the State Department. "I'm the only one that matters, because when it comes to it, that's what the policy is going to be. You've seen that, you've seen it strongly."

There's that half-in-jest line about there being no "I" in team, but there's really no "team" in the Trump White House. There is only Trump and his yes-people — or Trump and his former aides and Cabinet members.

Trump is a bully and imperious and thin-skinned and a proud Twitter troll — qualities that endear him to his most loyal supporters. In other words, he's kind of a jerk, and he has been for decades, to great advantage. For America and the Koreas, at least, he does genuinely seem to want peace — on his own terms, if that matters. There's amplereason for skepticism, but if "peace through jerkiness" works, great.